The present invention relates to a surgical template assembly and method for drilling and installing dental implants. More particularly, the invention relates a surgical template assembly and method for precisely drilling and installing dental implants using a surgical template assembly having one or more drill guides and one or more dental implant guides. The guides are located in the surgical template assembly by a computer-driven milling machine interfaced with computer-generated images of a patient's jawbone and a superimposed computer-generated simulation of one or more dental implants so that when the surgical template is placed in the patient's mouth a trajectory of the guides into the patient's jawbone corresponds to a trajectory of the computer-generated simulation of the one or more dental implants into the computer-generated image of the patient's jawbone.
Dental implants are devices which are surgically implanted into the jawbone of a patient in the areas where the patient is missing teeth. These devices mimic the roots of teeth and serve to support prosthetic caps, crowns, bridges or dentures. Dental implants are typically titanium metal-based and are generally cylindrical or screw-shaped in design.
Implants must be placed in a specific position and in alignment to the prospective teeth that they will eventually support. Therefore, the positioning of these dental implants must be precise to enable teeth to be made that will function properly and be esthetic in appearance.
Typically, a dental surgeon, after the gum is moved aside, uses a hand held drill to make a hole/osteotomy in the jawbone at the site that is to receive the dental implant. The hole that is drilled into in the patient's jawbone needs to have a defined trajectory, depth and diameter. These parameters are defined by the anticipated position of the patient's teeth to be replaced and supported by the implant(s), and existing anatomic structures, e.g., jawbone height and width, proximity to nerves, existing tooth roots, and sinus cavities.
It is recommended that a surgical template be used as a guide to assist the surgeon in positioning and angling the dental implant drill during dental implant surgery. However, some surgeons choose not to use a surgical template. Fabrication of a surgical template, which acts as a guide for this drilling procedure, generally includes the following steps:
1) Making a plastic replica of the prospective teeth; and PA1 2) Modifying the plastic replica teeth to allow guidance of the position and angulation of the dental implant drill through the replica teeth. This is accomplished by making hole(s) in the plastic replica teeth in the approximate area where the surgeon anticipates he or she will be placing the implant(s). PA1 1) Making a plastic replica of the prospective teeth to be supported by dental implants; and PA1 2) Placing radiopaque material in and/or on the plastic replica of the prospective teeth. This can be accomplished by applying a radiopaque paint, e.g., barium sulfate acrylic, to the surface of the replica or drilling a groove along the side of the replica and filling the groove with metallic dental filling material. PA1 1) Creating a plastic jaw model from the CT data. PA1 2) Determining the dental implant position manually. For example, by "eyeballing" the prospective implant position, the surgeon, via the use of a hand-held drill, drills a hole into the plastic jaw model. The surgeon then places a dummy implant into that hole. PA1 3) Lack of visualization of the prospective teeth to receive the dental implant support. For example, there is no coordination between prospective tooth position and dental implant position. PA1 4) Transferring the dental implant position to the surgical template by attaching cylinders to the top of dummy implants that were placed into the jawbone model.
If a computed tomography scan (CT scan) is to be taken of the patient's jawbone prior to implant surgery, it is recommended that a CT scan appliance is worn by the patient during the CT scan procedure. However, some surgeons choose to have their patients scanned without the use of a CT scan appliance.
Fabrication of a CT scan appliance generally includes the following steps:
Once the CT scan has been taken with the patient wearing the CT scan appliance, the CT scan data is reformatted via software to create various two-dimensional images, e.g., views along a cross-sectional, an axial, and a panoramic reference planes. A suitable software program to reformat the CT scan data is SIM/PLANT, manufactured by Columbia Scientific Inc. of Columbia, Md. The software program enables the surgeon to perform a dental implant simulation directly onto the reformatted CT scan images. In particular, the surgeon can view the position of the patient's jawbone, the dental implant simulation, and the image of the radiopaque material, e.g., the outline of the plastic replica. The CT scan appliance can now be modified, as described above, so that it becomes a surgical template.
At the time of surgery, the surgeon moves the gum away to expose the patient's jawbone. The surgeon then places the surgical template in the patient's mouth and to the best of his or her ability orients and guides the dental implant drill with the use of the surgical template.
In general, the dental implant drill is inserted through the hole in the surgical template and oriented by "eyeballing" the dental implant drill through the hole in the surgical template into the patient's jawbone. This procedure is not precise. The diameter of the holes made in the surgical template are usually much larger than the diameter of the implant drill bit.
In addition, during dental implant surgery the implant drill is manipulated by hand and in an up and down manner by the surgeon. Specifically, the surgeon "eyeballs" the three-dimensional trajectory/angulation of the implant drill bit relative to the surgical template and adjacent anatomic structures as he drills into the jawbone. The trajectory of the drill can be easily changed in an instant which can ruin the procedure. This aforementioned drilling process is fraught with the potential for many drilling errors which can undermine the success and even result in the failure of the overall procedure.
An attempt to increase the accuracy of locating a dental implant in a patient's jawbone is disclosed in U.S. Pat. No. 5,320,529 to Pompa. In particular, Pompa discloses a method of determining dental implant placement position by taking a CT scan of the patient's upper or lower jaw and then fabricating a model of that jaw from the reformatted CT scan data.
The model is made from a clear plastic/acrylic material into which the surgeon then drills a hole by hand. The surgeon then inserts a dental implant replica (a dummy implant) into the hole and inspects the dummy implant position for acceptability by looking at the dummy implant position through the clear model.
A cylinder is then attached to the top of the dummy implant and acrylic is added around the cylinder and on the surface of the jaw model. The acrylic piece with the encased cylinder now becomes a surgical template which rests on top of the patient's jawbone during the actual implant surgery.
Drawbacks with the method disclosed in Pompa include the following:
Thus, there is a need for a novel surgical template assembly and method which reduces, if not eliminates, the errors associated with the surgeon "eyeballing" the proper position and angulation of the drill during the drilling process of dental implant surgery. Furthermore, the novel surgical template assembly is enhanced by a system of interchangeable components for precisely guiding one or more drill bits, burs, bone taps, countersinks, other bone or soft-tissue drilling components, and the dental implant itself during the dental implant surgical procedure.